Brontosaurus

A giant on four legs

Brontosaurus was a huge, long-necked plant-eater that walked on four thick, pillar-like legs and trailed a long, whip-thin tail. Its neck bones were noticeably thicker than those of its close relatives Diplodocus and Apatosaurus. Like other sauropods, it carried a small head and peg-shaped teeth suited to stripping leaves rather than chewing them, and it likely swallowed plant material whole.

Its world

Brontosaurus lived in the Late Jurassic, roughly between 155 and 143 million years ago, in what is now the western United States. Fossils come from Wyoming, Colorado, Oklahoma, and Utah, all part of the Morrison Formation, a band of rock famous for its dinosaur remains. It shared this landscape with other sauropods such as Diplodocus, Apatosaurus, Brachiosaurus, and Camarasaurus, the plated Stegosaurus, and hunters including Allosaurus, Ceratosaurus, and Torvosaurus.

A name in dispute

Marsh named Brontosaurus in 1879. For most of the twentieth century, scientists treated it as the same animal as Apatosaurus, just described twice under different names. A later study of sauropod skeletons argued the two were different enough to count as separate genera, placing Brontosaurus close to Apatosaurus within the group Apatosaurinae. Not everyone agrees. Some paleontologists still consider Brontosaurus a synonym of Apatosaurus, and the question remains open.